This invention relates to a locking mechanism. The invention is described hereinafter with reference to a locking of a manhole cover but it is to be understood that this is merely by way of a non-limiting example. Other applications abound, eg. the locking of doors fixed to cabinets, containers, strong rooms and the like.
Manholes provide access to tunnels and passages which are used for vital components and services such as communication cables, electricity supplies, water and gas pipes and the like. If a manhole is breached and access is gained to this type of equipment the consequences can be serious.
It is known to lock a manhole cover to a surrounding frame. The lock which is used should, as far as is possible, be tamperproof. The frequency with which the lock is used, ie. locked and unlocked, may be high or low, depending on the circumstances. In many instances though a manhole cover will remain locked for a considerable period. The environmental conditions to which a manhole cover is exposed may also be severe and the cover may be subjected to a wide temperature range, the full effects of the weather eg. rain and snow, traffic and the like.
In explosive or hazardous environments the cover and the lock may also be required to be intrinsically safe.
It is apparent therefore that the provision of a lockable and secure manhole cover which is tamper-resistant and able to withstand a wide range of operating conditions is a challenging task.